Optical transmission method and optical transmission apparatus

The present application discloses example optical transmission apparatuses, where one example apparatus includes a filter, a router, and an optical multiplexer. The filter is connected to the router, and the router is connected to the optical multiplexer. The filter performs parity optical demultiplexing on 2N input optical signal groups by using 2N comb filters to obtain 2N odd optical signal groups and 2N even optical signal groups, and sends the 2N odd optical signal groups and the 2N even optical signal groups to the router. The router separately routes the 2N odd optical signal groups and the 2N even optical signal groups to the optical multiplexer by using at least four AWGRs. The optical multiplexer performs, by using 2N optical multiplexers, optical multiplexing on 4N optical signal groups output by the router to obtain 2N output optical signal groups.